A full mouth x-ray survey at birth typically reveals how many teeth?

At birth, an infant typically has around 20 primary (deciduous) teeth that are developing in the jaws, although they are not necessarily visible. This number encompasses all potential primary teeth that will eventually erupt as the child grows.

The discrepancy in answer choices lies in the common misconception about the visibility and timing of tooth eruption. Although babies may have only a few teeth that are visible when they start teething (around six months), the full complement of 20 primary teeth is already formed within the gums. By the time a child reaches about three years of age, all primary teeth typically erupt, making the full count of 20 primary teeth accurate for the context of the question regarding their presence at birth.

This understanding underlines the necessity of recognizing the full number of primary teeth that are genetically present, even if they are not erupted into the oral cavity at birth. Thus, the response indicating 20 teeth aligns with dental development knowledge.